N2-(4-Methoxysalicylidene)arginine hemihydrate

Abstract

The title compound, C14H20N4O4·0.5H2O [systematic name: (2S)-5-{[amino(iminiumyl)methyl]amino}-2-{[(1Z)-4-methoxy-2-oxidobenzylidene]azaniumyl}pentanoate hemihydrate], has been synthesized by the reaction of l-arginine and 4-methoxysalicylaldehyde and crystallizes with two independent substituted l-arginine molecules and one water molecule of solvation in the asymmetric unit. Each molecule exists as a zwitterion and adopts a Z configuration about the central C=N. The molecular conformation is stabilized by strong intramolecular N—H...O hydrogen bonds that generate S(6) and S(10) ring motifs. Intermolecular N—H...O and O—H...O hydrogen bonds involving also the water molecule and weak intermolecular C—H...Owater interactions link the molecules into an infinite one-dimensional ribbon structure extending along the b axis. The known (2S) absolute configuration for l-arginine was invoked. Weak intermolecular C—H...π interactions are also present.